Screening or separating machine.



v v J. J. GREBN.-

SCREENING OR SEPARA'II1\TGr MACHINE.

APPLIOAT1ON FILED JUNE 29, 1911.

Patented Mar. 5, 1912.-

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AP PLIOATION FILED JUNE 29 1911 1,019,041. Patented' Mar.5,191'2.

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JOSHUA J. GREEN, OF SHREVEPO'BT, LOUISIANA.

SCREENING R SEPARATING- MACHINE.

Specification of Letters Patent.

Patented Mar. 5, 1912.

Application filed .Tune 29, 1911. Serial No. 635,991.

To all whom it may concern:

Be it known that I, JosrrUA J. GREEN, of Shreveport, in the parish ofCaddo and State of Louisiana, ,have invented certain new and usefulImprovements in Screening or Separating Machines, of which the followingis a specification.

The screening machine in which my invention is comprised is one in whichthe screen proper is an endless traveling apron, the wire cloth, orother screening material, extending between and being secured at itsside edges to sprocket chains which pass around sprocket wheels (onepair at each end) mounted on suitable shafts, one of which is powerdriven for the purpose of imparting traveling motion to the screeningapron.

The screening operation takes place on the upper ply of the screeningapron, to which the material to be screened is delivered in any suitableway.

In order to support the chains so as to maintain a level screeningsurface, and at the same time to impart to that surface a jolting,shaking action to facilitate the screening operation, I arrange betweenthe two end sprocket wheels around which the endless traveling screenapron passes, small idler sprocket wheels, arranged below the upper plyof the screen toengage the sprocket chains, serving to uphold the chainsand keep them from sagging, and also being so proportioned relatively tothe chain links which they engage that the joint pin roller between anytwo links will pass beyond its seat on the sprocket before the nextsucceeding joint pin or roller meets its seat, thus permitting the chainby its weight to drop onto the sprocket, to be again slightly lifted asthe approaching joint pin or roller seats itself on the sprocket-theresult being that by this action of the idler sprockets and chains, arapid succession of jolts or knocks of the chains takes place, withconsequent agitation of the screening surface extending between andattached to said chains.

In the accompanying drawings to which I shall now refer for a betterunderstanding of my invention, I have represented so much of a machineembodying my improvements as needed for the purpose of explanation.

In said drawings-Figure 1 is a longitudinal vertical central section ofso much of a mixing machine as needed to illustrate my improvements,withthe screening surface in the position it occupies when the sprocketchains of the same are permitted to drop by the knocker sprockets Gr.Fig. 2 is a side elevation of the same with the screening surface in theposition it occupies when the chains are lifted by the seating of thecross rollers or joint pins of the links upon the knocker sprockets G.Fig. 3 is a plan of the machine. Fig. 4 is a transverse vertical sectionof the same. Fig. 5 is a perspective v1ew of the divided hopper whichreceives the screened material.

In the drawings, A, A are the shafts carrylng the two pairs of sprocketwheels B, B around which the endless screening apron passes. The shaftsA, A are supported in suitable frame work C, and the front shaft w1ll bepower driven, to revolve in the direction of the arrow 1, in Fig. 1. Thetwo sprocket wheels of each pair are secured upon their shaft at adistance apart from one another appropriate to the width of thescreening apron employed.

The screening apron consists of an endless apron D of wire cloth orother suitable screening material, and two endless sprocket chains whichpass around and engage the sprocket wheels B, B and B, B, and to whichthe side edges of the endless screening material D are secured in anyknown or suitable way. The apron travels in the direction of the arrow2, Fig. 1. I prefer that the front shaft A shall be below the plane ofthe rear shaft A, as shown, so that the upper ply of the screen surfaceshall slightly incline downward from rear to front-the arrow 8, Fig. 1,indicating the point at which the material to be screened is deliveredto the apron. If desired however, the screen may be horizontal insteadof inclined. It is preferred that the chains D should be roller chains,that is to say, should have rollers at the joints between adjoininglinks.

The upper ply of the endless apron forms the screening surface and thematerial which passes through the meshes of the screen isthe two pliesthereon to carry off the screened material; or other known or suitablemeans can be employed for the purpose.

Material too large to pass through the meshes of the screening apronwill be carried by the apron over the front of the machine, to bedelivered from that point as desired.

Below the upper ply of the screening apron, and arranged at suitableintervals apart, are pairs of small idler sprocket wheels G, mounted torevolve idle on cross shafts H, suitably fixed in the frame of themachine. There are three pairs of such idler sprockets in the presentinstance. They are arranged in the'longitudinal opening between the twoend sprocket wheels 13, B, in a position'to engage the portions of thesprocket chains of the upper ply between these sprocket wheels, and touphold the same and prevent them from sagging, said sprockets beingsubstantially tangential, or

nearly so, to the chains which they engage. It is preferred that thereshould be as many of these as practicable and placed as near to oneanother and to the large end sprocket wheels as good operation of thesame will permit, although I do not wish to be understood as"restricting myself to this arrangement.

The idler sprockets are small in diameter as compared with thedimensions of the links of the chains which they engagethat is to say,the length of the opening in said links. Take for example a chaincomposed of long links, having a six inch opening in each. I prefer, inorder to get the best results to use the smallest diameter of sprocketsmanufactured for that size of chain. The result is that when the screenis in movement, and the chains consequently are rotating the idlersprockets, the link joint pin or roller in front will have left thesprocket in its forward travel before the seat on the sprocket for thenext succeeding link will have risen high enough in its revolution toreach the plane of the underside of the chain. Consequently the chain atthis point and at this instant is unsupported and its weight, as well asthe tension, will cause it to drop onto the sprocket until the joint pinor roller brings up against its seat, when the continued revolution ofthe sprocket will again lift the chain at this point. In this way acontinuous up and down jolting of the chains is effected with the resultof corresponding continuous agitation of the screening surface Dextending between and secured to said chains, the violence oftheagitation depending upon the size of the sprocket as compared with thelength of the links of the chain with which it is used.

Thesmal-ler the diameter of the sprocket employed for a chain of givendimensions with which that sprocket is adapted to be used, the greaterwill be the jolting action.

The joint pins or rollers of the chain, by reason of their extendingbelow the plane of the links, also serve to induce this j olting action.The roller in front, slightly lifts the chain as it passes over thesmall portion of the periphery of the sprocket with which it contactstangentially, and as it leaves con tact with the sprocket before thenext succeeding roller meets the sprocket, the chain necessarily dropsuntil it brings up at some point against the sprocket. I use in practicea five or six tooth sprocket-preferably a five tooth sprocket, which isthe smallest made for a six inch link chainbut of course I do not wishto be understood as confining myself to a wheel of those precisedimensions. With a sprocket of that kind and a chain composed of sixinch links, each link will have a drop of 1% inches for every sprockettooth. Inasmuch as thirty inches (five links) of chain pass over asprocket wheel of five teeth at each revolution of the latter, then thesprocket wheel will make forty revolutions per minute when the chaintravels one hundred feet per minute. Hence, at this rate, two hundredlinks will, at their roller joints, rise and fall 1%- inches on eachsprocket every minute, thereby producing a lively jolting of the apron.I believe this combination of idler sprockets with the sprocket chainsof an endless apron, whereby the apron during its movement is kept incontinuous agitation, to be new with me irrespective of the use to whichit is putwhether as a conveyer and mixer, as set forth in my applicationfiled June 29, 1911, Serial No. 635,989 or as a screen, as set forthherein.

It will. be noted that in my machine, when in action the screeningsurface is constantly renewed by reason of the continuous travel of theendless apron, thus avoiding danger of the clogging of the meshes of thescreen, which exists when ordinary oscillating or vibrating screens areemployed or when the material to be sifted is delivered into theordinary revolving screen or bolt. And i11- deed the screen in mymachine can be kept clean mechanically without trouble, and withoutbeing stopped as in the case of ordinary screening machines, for thepurpose of brushing to open the meshes. For this purpose I may employ arotating brush, typified at K, on the return or under ply of the apronto mechanically brush the meshes of the screen during each cycle ofmovement of the apron. A device of this kind will be of use moreparticularly in cases where the material operated on is gummy and liableto clog. Where ordinary material is worked, I have found it suiticient,in order to keep the meshes clean, to occasionally hold a hand brushagainst the moving screen.

Having described my improvements and the best way now known to me ofcarrying the same into practical effect, I state in conclusion. that Ido not confine myself strictly to the structural details hereinbeforeshown and set forth in illustration of my invention; but

VVhat- I claim herein as new and desire to secure by Letters Patent isas follows:

The combination of endless sprocket chains, an endless apron extendingbetween and secured to said chains, driving sprocket wheels around whichthe sprocket chains pass and by which they aresupported, and idlersprockets of relatively small diameter and few teeth as compared withthe dimen sions of the chain links, located below the upper ply of theapron to engage tangentially, or substantially so, the chains, the apronderiving its support solely from the chains and sprockets, and the idlersprockets being arranged and operating substantially as described toimpart to the chains a jolting up and down movement With correspondingagitation of the apron.

In testimony whereof I affix my signature in presence of two witnesses.

JOSHUA J. GREEN. Witnesses It. P. Moonn, ED. SEAMAN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. G.

